1. Field of the Invention
The present invention relates to a method for producing a holder for an energy storage device.
2. Description of the Background Art
In modern HEV/EV vehicles (HEV=hybrid electric vehicle, EV=electric vehicle), Li-ion (lithium-ion) rechargeable batteries are likely to be used as energy storage devices in future. In these batteries, heating of the cells takes place during fast charging and discharging because of resistances both inside and outside the cells. However, temperatures above 50° C. damage these battery or rechargeable battery cells over the long term; for this reason, the cells should be cooled during operation. An attachment of a battery housing or rechargeable battery housing to a vehicle structure should be taken into consideration here. In this context, an attachment of these rechargeables or batteries should be designed as a car body-specific component in order to be able to be built into the vehicle easily. In the particular case, integration of a battery housing in the Smart car EV can be considered as an example. The primary focus here is on the dimensions and the mass of the battery cells.
For use in HEVs or EVs, essentially three different housing types for secondary Li-ion or Li polymer cells come into consideration: round cells with a hard housing; prismatic cells with a hard housing; or prismatic cells with a soft case made of aluminum composite film, so-called coffee bag cells.
Modern lithium-ion (rechargeable) cells are packed in a deep-drawn and/or welded housing of aluminum (generally with a wall thickness of 200-400 μm). Normally, the individual cells are then mounted on heat sinks (by gluing, for example). These heat sinks, in turn, are attached to a cooling plate (liquid cooling, evaporator plate, or tube evaporator), by which means the rechargeable cells can be cooled in operation.
While cells with a hard housing can be attached directly to the cooling plate by their top, bottom, or jacket, cells with an aluminum composite film require a heat sink for mechanical attachment. Some of the advantages with regard to weight and cost are negated as a result of these additionally required heat sinks. Moreover, the heat transfer from the cell to the heat sink is degraded by the adhesive layer.
Current battery housing concepts, due to the cell dimensions, are cumbersome and are not specifically tailored to the vehicle structure. As a result, attachment in the existing vehicle architecture is difficult, and generally is associated, with sacrifices in installation space or inefficient utilization of cubic volume.